a.
\(\left(-12\right).x-4=5^2.\left(-4\right)\)
\(\Leftrightarrow\left(-12\right).x-4=25.\left(-4\right)\)
\(\Leftrightarrow\left(-12\right).x-4=-100\)
\(\Leftrightarrow\left(-12\right).x=4-100\)
\(\Leftrightarrow\left(-12\right).x=-96\)
\(\Leftrightarrow x=\left(-96\right):\left(-12\right)\)
\(\Leftrightarrow x=8\)
b.
\(\left(-2015+184\right)-\left(84-2015\right)+\left(-200\right)\)
\(=\left(-2015+2015\right)+\left(184-84\right)+\left(-200\right)\)
\(=0+100+\left(-200\right)\)
\(=-100\)
a) (-12).x - 4 = 5².(-4)
-12x - 4 = 25.(-4)
-12x - 4 = -100
-12x = -100 + 4
-12x = -96
x = -96 : (-12)
x = 8